Lim kinases (Limk) are serine/threonine kinases which regulate microtubule stability and actin polymerization by phosphorylation and inactivation of actin binding proteins, the actin depolymerizing factor (ADF) and cofilin. The abnormal expression of either Limk isoform, Limk1 or Limk2, is implicated in numerous malfunctions that are related to a variety of diseases, such as glaucoma, ocular inflammation, cancer, primary pulmonary hypertension, intracranial aneurysms, Alzheimer's disease, and Williams syndrome. Lim kinases are downstream effectors of Rho kinases (ROCK). ROCK inhibitors have been demonstrated to be effective in reducing intraocular pressure (IOP) in recent years, and it is believed that this effect of ROCK inhibitors is through the Limk pathway. Unlike Rho kinases which have multiple substrates, Lim kinases serve as points of signal integration and channel this information to a select few substrates, which makes Lim kinases good targets for drug discovery with much less potential side effects. Despite the attractive potential of Limk inhibitors, there have been no small molecule inhibitors reported in peer-reviewed publications which showed simultaneously good potency, high selectivity, good solubility and appropriate DMPK properties for ocular and/or other CNS applications (such as good eye and/or brain penetration properties). In this application, we propose to develop novel small molecule Limk inhibitors based on a benzimidazole scaffold. Through the synthesis and evaluation of approximately 100 compounds total in two years, we anticipate discovering Limk inhibitors with biochemical IC50 values of <20 nM, cell-based IC50 values of <200 nM, good selectivity, excellent solubility, and with good eye and/or brain penetration properties. These compounds will serve as useful molecular tools to study the biological functions of Limk, and to probe ocular diseases and other Limk related CNS diseases. ) PUBLIC HEALTH RELEVANCE: The relevance of this project to public health is that it will provide useful tools to study ocular diseases and other central nervous system (CNS) diseases. Specifically, this research will discover potent and selective inhibitors of Lim kinase (Limk), which will be used as molecular probes to investigate Limk biology in the development and treatment of ocular diseases (glaucoma and ocular inflammation) and likely other Limk related CNS diseases. Eventually these probes can be used to facilitate the discovery of novel drugs to treat glaucoma and ocular inflammation.